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Published by Oak Ridge National Laboratory
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Editor: James A. Rome Issue 150 October 2015
E-Mail: jamesrome@gmail.com Phone (865) 482-5643
On the Web at http://www.ornl.gov/sci/fed/stelnews
14th Coordinated Working
Group Meeting
Warsaw, 17–19 June 2015
The 14th Coordinated Working Group Meeting
(CWGM14) was held 17–19 June 2015 at the Golden
Tulip Warsaw Center, hosted by the Institute of Plasma
Physics and Laser Microfusion (IPPLM, http://
www.ipplm.pl/en/). This was the first CWGM in Poland,
reflecting the expanded coordinated collaborations based
on EUROfusion, Mission 8: Stellarator. The IPPLM has
been especially known for its cutting-edge diagnostics
development. Thus, a dedicated diagnostics session was
held at this meeting to stimulate international collaborations
on diagnostics development and applications. Impurity
transport was the subject of the standing session, as
suggested and agreed to at the Stellarator-Heliotron Strategy
Workshop, Nagoya, March 2015 (see Stellarator
News, No. 147, April 2015). C. Hidalgo (CIEMAT) provided
a kick-off talk via remote video to raise critical
issues in impurity transport.
Session summaries and formulated action lists are presented
here. The presentation materials will be posted on
the EUROfusion wiki page, eventually.
Session summaries
Strategic Collaboration (A. Dinklage / F. Warmer)
The EUROfusion Mission 8 activities focus on the
exploitation of Wendelstein 7-X (W7-X) and actions
to prepare a physics basis for a HELIAS Fusion
Power Plant (FPP).
International collaborations within the work package
objectives can be supported by missions (mobility)
and resources (within the WPS1 activities). The IEA
Stellarator-Heliotron Implementing Agreement has
proven to be the right frame for joint actions.
The CWGM is proposed as a framework to prepare
further input to strategic discussions focused on reactor
issues such as:
• Common systems assessments
• Clarification of “road map” targets
Large Helical Device (LHD) (M. Yokoyama) is setting
up TASK3D-a to provide confinement and profile
data on a regular basis.
For the task of updating the International Stellarator/
Heliotron Profile Database with HSX data,
An interim responsible officer has been identified: F.
Warmer (IPP-Greifswald),
[https://ishpdb.ipp-hgw.mpg.de/ISHPDB/public/ ].
Alfvén Eigenmodes (AEs) and Energetic Particles
(S. Yamamoto)
Discussion focussed on aspects of AEs that we should
investigate to prepare for a stellarator-heliotron DEMO.
Effect of ECH/ECCD on AEs for control of AEs:
• TJ-II: “Impact of ECRH on the NBI-driven
Alfvén activity in the TJ-II stellarator: experiments
and data analysis” by Á. Cappa.
• Heliotron J: “External Control of Energetic-iondriven
MHD instabilities by ECH/ECCD in Heliotron
J Plasmas” by S. Yamamoto.
Fast ion generation by ICRF: “Fast-ion generation
with ICRF at Wendelstein 7-X in high-density
regimes” by Y. Kazakov.
Experiment (S. Masuzaki)
The status of Uragan 2M was presented by V. Moi-
In this issue . . .
14th Coordinated Working Group Meeting
Warsaw, 17–19 June 2015
The 14th CWGM was hosted by the Institute of
Plasma Physics and Laser Microfusion. Long-term
and short-term joint tasks were coordinated and
assigned. ................................................................. 1
This is the 150th issue of Stellarator News
The Editor wishes to thank the community. ............ 4
Stellarator News -2- October 2015
seenko. A dedicated RF conditioning study has been
conducted. A stellarator with an embedded mirror
configuration has been examined both experimentally
and numerically. This stellarator-mirror configuration
is envisioned as the basis for a fusion-fission hybrid
device.
Status of the development of 3D fluid code “Findif”
for edge plasma modeling was presented by G. Pelka.
Findif was applied to modeling the edge plasma in
TEXTOR DED and W7-X. Benchmarking is necessary.
S. Kumar presented a study of flows and electric
fields (Er) in HSX measured using Pfirsch-Schlüter
flows and motional Stark effect (MSE) polarimetry.
The measured Er was compared to the numerical simulation
data using the PENTA code. It is larger than
the numerically expected values near the core. Benchmarking
the Er calculated by SFINCS and FORTEC-
3D to the PENTA results is under way.
Impurities and Transport (N. Tamura)
Kick-off for the new standing session:
C. Hidalgo brought up important issues related to
impurity control. The question to be answered is:
“What are the optimum profiles for achieving high
fusion gain without impurity accumulation (high and
low Z) in stellarator-heliotron plasmas?”
LHD: The existence of an impurity transport boundary
layer inside the last closed flux surface (LCFS) is
suggested, which alters the accumulation of core-born
impurities.
HSX: Laser blow-off (LBO) and a system of 5 photodiode
arrays are ready for an impurity transport study
in HSX; collaborations (e.g., LBO system, STRAHL
analysis) are highly welcome.
Uragan 2M/Uragan 3M: U-2M suffers from impurities
from the wall, and U-3M indicated the possibility
of controlling impurities using RF heating.
Theory/Simulation
The importance of the parallel inertia force, which can
cause impurity density variations in stellarator/heliotron
plasmas, was highlighted.
The neoclassical-based impurity transport problem,
such as potential variations on a flux surface, etc., is
being numerically (EUTERPE, FORTEC-3D, ...) analyzed.
Diagnostics (M. Kubkowska)
W7-X: Limiter diagnostics including visible cameras
and a low-resolution near-infrared (NIR) camera for
plasma monitoring, wall inspection and thermography;
a higher-resolution camera for scrape-off layer
physics; a set of Langmuir probes; a pulse height
analysis (PHA) system; and a light impurities monitor
(for carbon and oxygen) were presented.
LHD: The following diagnostics systems were
described:
• Density and temperature, radial electric field and
rotational transform profiles: YAG Thomson scattering,
far infrared (FIR) and CO2 interferometer,
charge exchange spectroscopy (CXS), heavy ion
beam probe (HIBP), MSE
• Impurity: Infrared (IR) imaging bolometer, vacuum-
ultraviolet (VUV) spectrometer, extremeultraviolet
(EUV) spectrometer, CXS.
• Turbulence: HIBP, phase contrast imaging (PCI),
microwave frequency comb reflectometer, correlation
electron cyclotron emission (CECE), beam
emission spectroscopy (BES).
Heliotron J: Thomson scattering, CXS based on
Czerny-Turner spectrometer, Langmuir probe, BES,
60-channel soft X-ray system, and fast-ion diagnostics
were listed and described.
• In the PHA system for W7-X, Si drift detectors
will be used at the beginning. SiC or other detectors
could be considered as a candidate for the
deuterium campaign. Tests at LHD during the
deuterium campaign may be possible.
Application of gas electron multiplier (GEM) detectors
for soft X-ray measurements with energy discrimination
capability was presented. This kind of detector
could be interesting for W7-X diagnostics.
Scintillators for gamma-ray diagnostics were presented
in detail.
Fueling and Particle Transport (K. McCarthy)
4 talks showing growing collaborations on pellet
injection experiments and particle transport issues
involving LHD, W7-X, and TJ-II.
Review of the need to find means of avoiding hollow
density profiles in stellarators that can lead to discharge
termination (core pellet fueling, role of radial
electric field, and transport need to be considered in
detail).
Reports on pellet injection systems and recent
upgrades on LHD and TJ-II, with capabilities and limitations
of each system.
Reports on pellet fueling experiments conducted on
LHD and TJ-II that will provide input for presentation
at the coming International Stellarator/Heliotron
Workshop (ISHW).
Reports on data analysis by S. Cats and J.-L. Velasco
(somewhat preliminary) should be completed by
ISHW.
Discussion on pellet interaction in different plasmas
and on additional data that should be considered for
Stellarator News -3- October 2015
analysis (plasma pressure in TJ-II, neutral beam particles,
etc.).
Action List
Strategic Collaboration (A. Dinklage / F. Warmer)
Research issues for E documentation
• Global scaling of HSX data
• Renormalization factor, fren in the ISS04 (International
Scaling) for updated LHD and HSX data.
• Impact of plasma size (minor radius).
• TJ-II NBI shot data to be provided.
• Joint paper on configuration effects?
Update of profile database for code validation.
Alfvén Eigenmodes and Energetic Particles
(S. Yamamoto)
Short term:
Effect of ECH/ECCD on AEs for control of AEs:
LHD, TJ-II, Heliotron J.
We should apply the same method, targeting similar
modes to obtain unified knowledge.
Link to ITPA-EP (energetic particles) group, by S.
Yamamoto and K. Nagaoka.
Long term:
Identification and parameter dependence of observed
modes (excited by ions):
• High magnetic shear: LHD [EGAM, BAE, EPM,
GAE/RSAE, TAE, HAE]: K. Ogawa, K. Nagaoka.
• Low magnetic shear, low iota, Heliotron J [BAE?,
EPM, GAE]: S.Yamamoto.
• Low magnetic shear, high iota, TJ-II [GAE,
HAE]: Á. Cappa, A.V. Melnikov, B. J. Sun.
Loss mechanism of fast ions caused by AEs using
lost-ion probe (LIP)/fast-ion loss detector (FILD).
LHD, CHS, Heliotron J (currently Japanese domestic
collaboration/joint experiment): S. Yamamoto, K.
Ogawa.
Prediction of AEs and their effect on particles in a
stellarator/heliotron DEMO.
Experiment: Parameter dependence of observed AEs
such as an observation region consisting of dimensionless
parameters.
Simulation: Development of numerical codes for the
prediction of AEs in the DEMO (need collaboration
with D. A. Spong, Y.Todo, A. Könies, and others).
Impurities and Transport (N. Tamura)
Short term
Experiment: Formulation of joint experiments
• Resurvey and recharacterization of heating effects
on impurity accumulation. (LHD, W7-X, TJ-II,
Heliotron J, HSX, Uragan-2M/3M).
• Turbulence characterization focusing on impurity
transport (LHD, W7-X, TJ-II, Heliotron J, HSX).
Theory/simulation: Feasibility study of a joint paper
regarding non-uniform potential and density on flux
surface for IAEA-FEC2016 (Kyoto).
Long term
Experiment: Acquisition of an optimized heating
scheme (power, deposition location) for the suppression
of impurity accumulation.
Ensuring compatibility between a power exhaust scenario
(detachment) and an impurity handling scenario.
Theory/simulation: Strategy for impurity code validation
(improvement in prediction accuracy).
Production of an optimum profile from the viewpoint
of impurity transport.
Fueling and Particle Transport (K. McCarthy)
Perform simultaneous pellet/impurity injection experiments
to determine how fueled particle/impurity confinement
might be related.
For ISHW presentation, K. McCarthy will need to
know the internal deadline of the LHD Experiment
Group and also need to consider the EUROfusion
deadline.
Consider possibility of a joint paper on pellet injection
comparisons on LHD and TJ-II (after ISHW).
Acknowledgements
We sincerely appreciate all the efforts made by the local
organizers (IPPLM). The 14th CWGM was financially
supported by the Polish Ministry of Science and Higher
Education within the framework of the National Contact
Point Euratom-Fusion located in IPPLM. It was also supported
by the National Institute for Fusion Science and the
National Institutes of Natural Sciences under the project,
“Promotion of the International Collaborative Research
Network Formation.” The participation of Arturo Alonso,
Andreas Dinklage, and Jose-Luis Velásco was supported
by EUROfusion. This work has been partly carried out
within the framework of the EUROfusion Consortium and
has received funding from the Euratom research and training
programme 2014–2018 under grant agreement
633053. The views and opinions expressed herein do not
necessarily reflect those of the European Commission.
Agata Czarnecka (IPPLM) and Arturo Alonso (CIEMAT) on
behalf of all participants in the 14th CWGM
Stellarator News -4- October 2015
Wendelstein 7-X article in Science
News
http://news.sciencemag.org/physics/2015/10/featurebizarre-
reactor-might-save-nuclear-fusion
This is the 150th issue of
Stellarator News
This is the 150th issue of Stellarator News (SN). The purpose
of SN has always been twofold:
To offer a fast track for the publication of results in
stellarator/heliotron experiment, theory, engineering,
and even speculation.
To help coordinate the activities of the stellarator
community. The CWGM meeting report in this issue
is an excellent example of this coordination aspect.
I want to thank the many contributors to SN, some of
whom (including myself) have retired over the intervening
years. I encourage any reader of SN to send contributions
to me.
A special thanks must go to my incredible technical editor
Margaret (Bonnie) Nestor who has edited every issue of
SN. After I piece together the issue and fix obvious problems,
Bonnie works her magic. Bonnie used to edit Fusion
Energy Division publications, and is now Assistant to the
ORNL Laboratory Director, Thom Mason. Bonnie’s editing
of your paper into correct, concise, and clear English is
a special advantage of contributing to SN!
Again thank you Stellarator Community for your help over
the years.
James A. Rome, Editor
E-Mail: jamesrome@gmail.com
Participants attending the 14th Coordinated Working Group Meeting held in Warsaw, Poland 17–19 June 2015.